[aprssig] findU tide support

[Steve Dimse]

Ok, got some tide support working. Xtide uses a full test lookup,  
which is a real pain for URLs, so my code uses an index number. To  
search for a keyword, use this URL:

http://www.findu.com/cgi-bin/tidestation.cgi?name=cudjoe

You can also find the nearest to a callsign with

http://www.findu.com/cgi-bin/tidestation.cgi?call=k4hg

or a given location with

http://www.findu.com/cgi-bin/tidestation.cgi?lat=24.6&lon=-81.5

Comments and suggestions welcome...

Steve K4HG